NEW YORK, Sept 11: New Yorkers gathered at the Ground Zero to observe the second anniversary of the Sept 11 attacks on the US landmarks that had left 2,792 people dead.

But a new fear struck the people as a new audiotape and video footage of Al-Qaeda chief Osama bin Laden surfaced on Wednesday in which Americans were warned of more horrific attacks.

Osama’s top lieutenant, Ayman Al-Zawahiri, issued a dire warning saying that Al Qaeda’s attacks so far were mere “skirmishes.”

“The true epic has not begun,” Zawahiri said, calling on Muslims to join the fight and “devour the Americans as lions do and bury them in the Iraqi graveyard.

“On the second anniversary of the raids on New York and Washington, we challenge America and its crusade, which is teetering from its wounds in Afghanistan and Iraq,” said a voice purported to be Zawahiri’s.

It was the first time Osama bin Laden has been seen since November 2001, and his reappearance on the eve of the 9/11 anniversary rattled nerves.

As word of the tape spread to Wall Street, stocks plunged, the Nasdaq posted its biggest drop in two months.

Airlines already cancelled numerous flights because leery passengers were refusing to fly.

A woman who lost her daughter, said the new tape made her uneasy.

“Like most New Yorkers, I still have anxiety because I feel New York City is a target,” she said. “It makes me angry toward those people who have targeted us.” Another woman said the tape was a reminder of how her world has changed.

“Everything will never get back to normal,” she said.

A US intelligence official said that while some Al Qaeda tapes have preceded attacks, there was no indication of any imminent threats.

“I haven’t seen anything out of the ordinary,” the official told the Daily News. An FBI official added: “I’m unaware of any heightened concern regarding any specific information about new attacks around the 9/11 anniversary.”

A Homeland Security Department spokesman said there were no plans to raise the terror threat code above its current “elevated” yellow.

The CIA — which believes Osama is hiding among the mountain peaks along the Afghanistan-Pakistan border — was analysing the tapes yesterday.

The Sept 11 ceremony opened with two bagpipers and a drummer marching onto the site of the World Trade Center, bearing an American flag that once flew over its ruins.

“We come here to honour those that we lost, and to remember this day with sorrow,” New York City’s Mayor Michael Bloomberg said.

Minutes later, people attending the anniversary ceremony at the Ground Zero paused for a moment of silence.